Suggestions to Preston Briggs
This site was last updated on February 15, 2008.
One of the innovations used in the Son of Snort is an O-beam spar. It's doubly tapered, from the center to each of the tips, and resists twisting far better than common alternatives. As a bonus, we're able to put the bladder inside the spar, keeping the weight of the fuel at the CG and protecting the foam wing from the nitro, in case of a burst bladder.
The complete spar is assembled from three parts: two identical half spars and a joiner (the spiral lines are due to the way the half spars are molded, not the lay of the CF cloth).
Still under construction
The half spars weight 28 grams each, and the joiner weighs 11 grams.
After the epoxy has cured, we can unwind the Fascal.
The spar is cut to length using this jig. By incorporating a spar joiner part in the jig, we can ensure a precise fit in the future.
Here's a spar in the jig, ready to be cut.
We need a few slots in the inboard half, to allow clearance for the bellcrank and the leadouts. The area around the slots is reinforced with additional carbon fiber. We cut the slots using a Dremel tool, guided by this fiberglass piece that slips over a spar.
Here are the slots. Notice that the spar joiner is slotted to match.
Here's how all the pieces will eventually fit together.
